X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavutil%2Fcrc.c;h=ee925d6b8a2cb44ab5ccd537577849e1c435fbd8;hb=17aa02b9a112398f8d9f74dcb3db55c31e91c8fe;hp=5ccf03639b0cbae68706cb77fa12071162b325f4;hpb=3abe5fbdc4169047421e9e8794a8f190d794b929;p=ffmpeg diff --git a/libavutil/crc.c b/libavutil/crc.c index 5ccf03639b0..ee925d6b8a2 100644 --- a/libavutil/crc.c +++ b/libavutil/crc.c @@ -1,27 +1,29 @@ /* * copyright (c) 2006 Michael Niedermayer * - * This file is part of FFmpeg. + * This file is part of Libav. * - * FFmpeg is free software; you can redistribute it and/or + * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * - * FFmpeg is distributed in the hope that it will be useful, + * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public - * License along with FFmpeg; if not, write to the Free Software + * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ +#include "config.h" #include "common.h" +#include "bswap.h" #include "crc.h" -#ifdef CONFIG_HARDCODED_TABLES +#if CONFIG_HARDCODED_TABLES #include "crc_data.h" #else static struct { @@ -39,46 +41,49 @@ static AVCRC av_crc_table[AV_CRC_MAX][257]; #endif /** - * Inits a crc table. - * @param ctx must be an array of sizeof(AVCRC)*257 or sizeof(AVCRC)*1024 - * @param cts_size size of ctx in bytes - * @param le if 1, lowest bit represents coefficient for highest exponent - * of corresponding polynomial (both for poly and actual CRC). - * If 0, you must swap the crc parameter and the result of av_crc + * Initialize a CRC table. + * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024 + * @param le If 1, the lowest bit represents the coefficient for the highest + * exponent of the corresponding polynomial (both for poly and + * actual CRC). + * If 0, you must swap the CRC parameter and the result of av_crc * if you need the standard representation (can be simplified in * most cases to e.g. bswap16): - * bswap_32(crc << (32-bits)) + * av_bswap32(crc << (32-bits)) * @param bits number of bits for the CRC * @param poly generator polynomial without the x**bits coefficient, in the * representation as specified by le + * @param ctx_size size of ctx in bytes * @return <0 on failure */ -int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size){ - int i, j; +int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size) +{ + unsigned i, j; uint32_t c; - if (bits < 8 || bits > 32 || poly >= (1LL< 32 || poly >= (1LL << bits)) return -1; - if (ctx_size != sizeof(AVCRC)*257 && ctx_size != sizeof(AVCRC)*1024) + if (ctx_size != sizeof(AVCRC) * 257 && ctx_size != sizeof(AVCRC) * 1024) return -1; for (i = 0; i < 256; i++) { if (le) { for (c = i, j = 0; j < 8; j++) - c = (c>>1)^(poly & (-(c&1))); + c = (c >> 1) ^ (poly & (-(c & 1))); ctx[i] = c; } else { for (c = i << 24, j = 0; j < 8; j++) - c = (c<<1) ^ ((poly<<(32-bits)) & (((int32_t)c)>>31) ); - ctx[i] = bswap_32(c); + c = (c << 1) ^ ((poly << (32 - bits)) & (((int32_t) c) >> 31)); + ctx[i] = av_bswap32(c); } } - ctx[256]=1; -#ifndef CONFIG_SMALL - if(ctx_size >= sizeof(AVCRC)*1024) + ctx[256] = 1; +#if !CONFIG_SMALL + if (ctx_size >= sizeof(AVCRC) * 1024) for (i = 0; i < 256; i++) - for(j=0; j<3; j++) - ctx[256*(j+1) + i]= (ctx[256*j + i]>>8) ^ ctx[ ctx[256*j + i]&0xFF ]; + for (j = 0; j < 3; j++) + ctx[256 *(j + 1) + i] = + (ctx[256 * j + i] >> 8) ^ ctx[ctx[256 * j + i] & 0xFF]; #endif return 0; @@ -89,9 +94,10 @@ int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size){ * @param crc_id ID of a standard CRC * @return a pointer to the CRC table or NULL on failure */ -const AVCRC *av_crc_get_table(AVCRCId crc_id){ -#ifndef CONFIG_HARDCODED_TABLES - if (!av_crc_table[crc_id][sizeof(av_crc_table[crc_id])-1]) +const AVCRC *av_crc_get_table(AVCRCId crc_id) +{ +#if !CONFIG_HARDCODED_TABLES + if (!av_crc_table[crc_id][FF_ARRAY_ELEMS(av_crc_table[crc_id]) - 1]) if (av_crc_init(av_crc_table[crc_id], av_crc_table_params[crc_id].le, av_crc_table_params[crc_id].bits, @@ -103,48 +109,57 @@ const AVCRC *av_crc_get_table(AVCRCId crc_id){ } /** - * Calculate the CRC of a block - * @param crc CRC of previous blocks if any or initial value for CRC. + * Calculate the CRC of a block. + * @param crc CRC of previous blocks if any or initial value for CRC * @return CRC updated with the data from the given block * * @see av_crc_init() "le" parameter */ -uint32_t av_crc(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length){ - const uint8_t *end= buffer+length; +uint32_t av_crc(const AVCRC *ctx, uint32_t crc, + const uint8_t *buffer, size_t length) +{ + const uint8_t *end = buffer + length; -#ifndef CONFIG_SMALL - if(!ctx[256]) - while(buffer>8 )&0xFF)] - ^ctx[1*256 + ((crc>>16)&0xFF)] - ^ctx[0*256 + ((crc>>24) )]; +#if !CONFIG_SMALL + if (!ctx[256]) { + while (((intptr_t) buffer & 3) && buffer < end) + crc = ctx[((uint8_t) crc) ^ *buffer++] ^ (crc >> 8); + + while (buffer < end - 3) { + crc ^= av_le2ne32(*(const uint32_t *) buffer); buffer += 4; + crc = ctx[3 * 256 + ( crc & 0xFF)] ^ + ctx[2 * 256 + ((crc >> 8 ) & 0xFF)] ^ + ctx[1 * 256 + ((crc >> 16) & 0xFF)] ^ + ctx[0 * 256 + ((crc >> 24) )]; } + } #endif - while(buffer> 8); + while (buffer < end) + crc = ctx[((uint8_t) crc) ^ *buffer++] ^ (crc >> 8); return crc; } #ifdef TEST #undef printf -main(void){ +int main(void) +{ uint8_t buf[1999]; int i; - int p[4][3]={{AV_CRC_32_IEEE_LE, 0xEDB88320, 0x3D5CDD04}, - {AV_CRC_32_IEEE , 0x04C11DB7, 0xC0F5BAE0}, - {AV_CRC_16_ANSI , 0x8005, 0x1FBB }, - {AV_CRC_8_ATM , 0x07, 0xE3 },}; + int p[4][3] = { { AV_CRC_32_IEEE_LE, 0xEDB88320, 0x3D5CDD04 }, + { AV_CRC_32_IEEE , 0x04C11DB7, 0xC0F5BAE0 }, + { AV_CRC_16_ANSI , 0x8005 , 0x1FBB }, + { AV_CRC_8_ATM , 0x07 , 0xE3 } + }; const AVCRC *ctx; - for(i=0; i